The present invention relates generally to valving systems for internal combustion engines, and more particularly to the integration of mono valves with fuel injectors and port control valves.
Engineers are constantly looking for ways to improve the efficiency and performance of internal combustion engines. Several conflicting demands on some engines have placed undesirable spatial limitations relating to the intake and exhaust valves as well as the incorporation of a suitable fuel injection system. In many diesel type engines, four gas exchange valves (two intake and two exhaust) surround a centrally mounted fuel injector whose tip protrudes directly into the hollow piston""s cylinder. Because manufacturing constraints generally restrict each of the valves and fuel injectors to a circular cross section, the size of these components is limited by each other and the size of the piston for a given engine. These spatial constraints often result in compromises between the valves and fuel injector that result in an engine with less efficiency and lower performance levels than should otherwise be possible.
In many engines, both the gas exchange valves and the fuel injection system are coupled in their operation to the crank shaft angle of the engine. In other words, in many engines these components are driven to operate by a rotating cam that is driven to rotate directly by the engine. Engineers have recognized that combustion efficiency and overall engine performance can be improved by decoupling the operation of the fuel injection system from the rotation angle of the engine. In this regard, Caterpillar, Inc. of Peoria has seen considerable success by incorporating hydraulically-actuated electronically-controlled fuel injectors into engines. These fuel injection systems allow an engine computer to inject a calculated amount of fuel, often in a pre-determined way, into the combustion space in a timing that is based upon sensed operating conditions and other parameters.
In part because of the gains observed by the incorporation of hydraulically-actuated electronically-controlled fuel injectors, engine research has shown that further improvements in performance and efficiency can be gained by also decoupling the gas exchange valves from the engine rotation angle. In other words, it is also desirable that the gas exchange valves be electronically controlled in order to control exhaust and intake portions of the engine cycle independent of the engine crank shaft angle. This could allow the intake and exhaust portions of the engine cycle to be optimized for a particular operating condition and other parameters, such as temperatures, and load/speed conditions, etc. The present invention is directed to overcoming these and other problems, as well as improving the efficiency and performance of engines in general.
In one aspect, an engine has a casing that defines a hollow piston cavity separated from an exhaust passage and an intake passage by a valve seat. A gas exchange valve member is positioned adjacent the valve seat and is moveable between an open position and a closed position. The gas exchange valve member defines an opening that opens into the hollow piston cavity. A needle valve member is positioned in the gas exchange valve member adjacent a nozzle outlet, and is moveable between an inject position and a blocked position. A port control valve member has a port control hydraulic surface and is mounted around the gas exchange valve member. The port control valve is moveable between an intake position at which the exhaust passage is blocked, and an exhaust position at which the intake passage is blocked. A pilot valve is moveable between a first position at which the port control hydraulic surface is exposed to a source of high pressure fluid, and a second position at which the port control hydraulic surface is exposed to a source of low pressure fluid.
In an another aspect, a valve includes a valve body that defines a first passage and a control passage. A valve member is positioned in the valve body and includes a first hydraulic surface, a control hydraulic surface and a second surface. The valve member is moveable between an up position and a down position. The first hydraulic surface is exposed to fluid pressure in the first passage when the valve member is in its down position, but only a portion of the first hydraulic surface is exposed to fluid pressure in the first passage when the valve member is in its up position. The control hydraulic surface is exposed to fluid pressure in the control passage. The valve also includes a source of low pressure fluid, a source of high pressure fluid and a biaser in contact with the second surface. The valve member is biased toward its down position when the valve member is in its down position and the first passage is fluidly connected to the source of high pressure fluid. The valve member is biased toward its down position when the valve member is in its up position, the first passage is fluidly connected to the source of high pressure fluid and the control passage is fluidly connected to the source of high pressure fluid. The valve member is biased toward its up position when the valve member is in its up position, the first passage is fluidly connected to the source of high pressure fluid and the control passage is fluidly connected to the source of low pressure fluid.
In still another aspect, an electronically controlled device includes a body and a port control valve member movably positioned in the body. A gas exchange valve member is at least partially positioned in the port control valve member. A fuel injector has a direct control needle valve and is at least partially positioned in the gas exchange valve member. A first electrical actuator is operably coupled to the direct control needle valve. A second electrical actuator is operably coupled to the gas exchange valve member and the port control valve.